Conventional window frames for jumbo aircraft are produced of aluminum sheet metal by die stamping operations, particularly for reasons of economy. However, due to the smaller density of carbon fiber reinforced composite materials which have a mechanical strength or stiffness similar to that of aluminum, one can expect to achieve a significantly smaller weight for structural components made of carbon fiber composite materials by respective production processes. Such processes involve cutting to size material patterns which are then precisely stacked one on top of the other. In order to achieve a torsion stiffness a carbon short fiber core prepreg material is used. However, such a short fiber prepreg has low mechanical characteristics and adds to the weight of the finished component. These carbon fiber composite processes or technologies achieve the required mechanical characteristics, however, the production under economically sustainable conditions has not been possible heretofore. Thus, the disadvantages of conventional fiber composite constructions are seen in the high effort and expense for manual operations and in the inadequate assurance that quality requirements are satisfied. However, the low weight of the structural components is an advantage particularly in aircraft construction.
Fiber textile materials have been tested for some time now, for example for the production of aircraft frame ribs. The main reason for the use of such textile materials is their drapability or deformability. However, substantial difficulties are encountered in the large scale use of fibers which are assembled according to the so-called tailored fiber placement methods, whereby the fibers are laid down and sewn together. The same difficulties are encountered when using spirally woven fabrics which are used in order to form reinforcements around a hole in the structural component. These difficulties are seen particularly in the expensive and involved production of the semifinished products and generally in the working of the fibers. In connection with the production of spirally woven fabrics, particularly an oval geometry of the frame to be formed entails substantial limitations with regard to the availability of such fabrics due to the complexity and the comparably expensive semifinished product manufactured by weaving or knitting. The tailored fiber placement method is at present still not suitable for a large scale production due to its low fiber depositing or layering speeds. Another disadvantage of the tailored fiber placement method is seen in that substantial inhomogenities in the fiber distribution and fiber orientation in the body of the layered fibers result when these layered fibers are shaped into a curved structure.